The Complete Guide to Peptides – How Are They Different Than Protein?

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Peptide bond guide

When involved in any lengthy discussion or research dealing with proteins, eventually the word “peptides” comes up. At first, this term may seem a bit confusion but peptides closely relate to proteins and by the end of this article you’ll have a firm understanding on what peptides are, why they’re important and how they’re unique.


What Are Peptides?

Simply, peptides are chains of amino acids that have been combined together by a peptide bond (amide). How many amino acids are in each bond? Well that varies, but these amino acid chains, or peptides, are broken down into two categories based on their length:

  • Oligopeptides - These are amino acid chains that are relatively short in length (“oligo” mean few). These are chains that contain a small number of amino acids; this number is typically 10 or less.
  • Polypeptides - These are the amino acid chains that contain more than 10 amino acids. Polypeptides are defined as amino acid chains of reasonable length.

Some scientists elect to simplify the terminology by referring to oligopeptides as just, peptides and polypeptides as polypeptides.

It’s also worth noting that a dipeptide is two amino acids combined by a peptide bond and tripeptides are a three amino acid chain.

How Peptides Are Formed

Peptides can be be formed within the body as well as in a laboratory. In the body, peptides form naturally and perform in functions like hormones and neurotransmitters. The peptide bond that combines the two amino acids is a covalent bond. This occurs when the C-terminus of one of the amino acids reacts to the N-terminus of another amino acid in which a water molecule is released, thus the peptide is formed.

Liquid phase peptide synthesis and solid phase peptide synthesis allow laboratories to develop a large variety of unique peptide bonds. Though, solid phase peptide synthesis is most commonly used in the lab.

Peptides vs Proteins

This is where it gets a bit interesting. As you probably know proteins are made up of amino acids as well, so what’s the difference between peptides and proteins?

Well, it really comes down the structure and size of the amino acid chains. In simple terms, peptides are smaller amino acid chains and proteins are longer amino acid chains.

Polypeptides that are around 50 amino acids in length (or longer) can generally be defined as a protein. Therefore, amino acids of about 50 or more, are defined as proteins.

Another differentiating factor between between peptides and proteins is their structure. Polypeptides that are shorter than 50 amino acids, typically do not fold and become a fixed structure.

Proteins on the other hand, due to their length being over 50 amino acids, fold into a fixed structure. This fixed structure differentiates proteins from peptides. These fixed structures that proteins possess often serve important functions. 

Should You Use Peptide Supplements?

Amino acids supplements are widely popular with athletes, but are peptides supplements? Especially considering peptide supplements are made up of amino acids. 

An advantage over protein is that peptides can be broken down and absorbed by the body faster than protein. Additionally, sometimes peptides can be broken down and absorbed faster than amino acid supplements due to peptides receptors in the body.

There are variations of creatine and glutamine peptide supplements that can be beneficial to the body, and efficiently. You can even get “pre-digested” peptide supplements that are typically pills that consist of many of the popular amino acids in an easy to digest form.

Completing Your Understanding

In all, peptides are a very important amino acid chain. When it comes to proteins, you can refer to proteins as polypeptides because they’re similar, but scientifically peptides and proteins are different. 

Peptides can be found is so many aspects of our lives. They’re found in our bodies, foods we eat and even supplements. They’re very important to how we grow and function by playing a roles in fitness topics like muscle growth, fan burning and endurance.